Electric heating device.



W. s. HADAWAY, JR. ELECTRIC HEATING DEVICE. APPLIUATION FAILED JULY 24,1908.

ATTOlNEY I 111 STATES PATENT orrron.

WILLIAMS. HADAWAY, an, or EAST ORANGE, EW JERSEY, ASSIGNOB, BY MESNLASSIGNMENTS, r0 wnsrmenonsn unaware & MANUFACTURING COMPANY, A

CORPORATION or PENNSYLVANIA.

nnncrar'c HEATING nnvxcn.

- Specification of Letters Patent.- Application ma my 24, 190;.serials). 445,200.

- shall be simple and durable in construction and adapted for eneralheating purposes.

The heating device of my present invention comprises a metal cylinder towhich heat is imparted by resistance ribbon that is insulated from itsouter surface and is suitably disposed on the insulation in a zigzagform and held in 'osition under heavy pressure by any suita le means,such as steel band wire which is closely wrapped around the 1 cylinderand resistance element.

By constructing my improved heating de-' vice as above indicated, I amable to utilize a maximum amount of the heat which is generated in theresistance element, the pressures established by the band wire beingsuf- Lcient to prevent any relative movement between the several partsof the device on ac count of unequal expansion and contraction whichusually occur'in devices of this character.

Figure 1 of theaccompanying drawings -is a planview, and Fig.2 a sideelevation, of an electric heating deviceconstructed in accordance withmy invention, the wrappings of insulating material and the metal armorbeing broken awayin' Fig. 2 to .d-isclosethe,

resistance ribbon Fig. 3 is a sectional View on the line II IIII ofFig.2, and Fig. 4 is a detail view of the resistance ribbon which ispartially disclosed in Fig. 2.

Referring to the drawings, the device here illustrated comprises ahollow cylinder '1,

preferably constructed of sheet iron or other eat-conducting material,having st-ifi'ening rings 2 and 3 around which its ends are bent, awrappin 4 of insulating fabric, a resistance strlp orribbon 5 and ametal armor 6, which' is wrapped around the cylinder after theresistance is properly disposed on the insulating wrapping 4, as heremaer set iforth. It may be desirable to use :1 cyl inder of tile or, otherelectrical non-conductor in lieu of the conducting cylinder.

The resistance strip or ribbon' 5 is preferably constructed of a steelband or ribbon- Patented July 29, 1913.

which is provided with a plurality of slots 7 and 8 that extend inwardlyfrom opposite edges and are arranged alternately so that a zigzagcurrent-conducting ath is provided.

As shown in the drawings, t isribbon is laid on the insulating wrapping4 in a zigzag form, the center lines of the main portions of the zigzagstrip being parallel to the axis of the cylinder, but, while this formis considered preferable, it is not essential to my invention. The slots'7 and 8 are omitted at the bends of the strip (see Fig. 4) so that amaterially greater current-carrying capacity is produced andthe dangerof overheating and rupturing the strip at these points is avoided. Forthe same reason, the

slits 7 and 8 are also omitted from the ends .This sheet metal plateconstitutes a portion of the armor 6 which further comprises a pluralityof turns of steel band wire. 15 that are closelywound around the outersurface of the cylinder after the parts 4, 5, 6 and 13 v are inposition. The primaryobject' ofthe steel band wire 15 is tocreate arelatively heavy pressure'between the metal cylinder 1 and theresistance ribbon, which are only separated by a thin wrapping ofinsulation,

in order to insure a uniform. expansion of;

the two parts and a transfer of a maximum amount of the heat generatedin the resistance ribbon to the metallic walls of the cylinder that areexposed to the air or to some other liquid or fluid which it is desiredto heat. Metal bands or rings may be shrunk onto the cylinder, toproduce the desired pressure, instead of the band wirin As illustratedin Figs. 2 and 3, one en of the cylinder is provided with an enlargement16 to which the terminal members 11 and- 12 are secured, holes 17 beingprovided. in the shoulderformed at'the junction of the enlargement withthe cylinder, through which the resistance leads 9 and w 10 extend. Theends of the band wlre are secured to binding screws 17 and 18. Thethickness of the insulation on the outer surface of the assembledresistance unit may be greater or less, according to the use for whichthe heater is intended. When it is used to heat water or other liquidsflowing through it, the radiation of heat from the outer surface isprevented as far as possible.

While I believe that the resistance ribbon illustrated is preferable foruse with my is improved heating device, my invention is not restrictedto its use, and any suitable form of resistance element may be employed.It is also conceivable that structural modifications may be effected inthe heating de- 20 vice itself Within the spirit and scope of ,myinvention.

I claim as my invention:

1. An electric heating device comprising a cylinder of heat-conductingmaterial, a

5 resistance element disposed on the surface.

thereof and insulated therefrom, and acompression metal sheath for theassembled cylinder and its resistance element comprising turns of wiredisposed in compact side-by- 0 side relation and under tension.

2. An electric heating device comprising a hollow metal cyliiider, aresistance strip or ribbon disposed on its outer surface and insulatedtherefrom, a plate of heat-conductmg material wrapped around thecylinder and the resistance and electrically separated from the latter,and a wrapping of band wire for pressing the resistance strip or ribbonagainst the outer surface of the cylinder.

3. An electric heating device comprising a metal tube or cylinder, azigzag resistance strip or ribbon disposed on the outer surface of thecylinder and insulated therefrom, the center line of the ribbon beingparallel to the axis of the cylinder, successive wrappings of.insulating and heat-conducting material wound over the resistance strip,and

a close Wrapping of band wire surrounding the assembled device andforcing its parts together to increase the heat-conductivity from theresistance ribbon to the walls of the cylinder.

l. An electric heating device comprising a sheet metal cylinder, aninsulating wrapping on its outer surface which is uninjured at hightemperatures, resistance strip or ribbon laid on the surface of thecylinder from end to end in a zigzag form, said ribbon being. providedwith a plurality of slots which extend inwardly from opposite edges andare arranged alternately to increase the length of thecurrent-conducting path therethrough, and successive wrappings ofinsulation and sheet metal and an outer wrapping of band wire forpressing the other parts together.

5. An electric heating device comprising a hollow cylinder, a resistancestrip or ribbon disposed on its outer surface and insulated therefrom, aplate of heat-conducting material wrapped around the cylinder and theresistance and electrically separated from the latter, and a wrapping ofband wirefor pressing the resistance strip or ribbon against the outersurface of the cylinder.

6. An electric heating device comprising a tube or cylinder, a zigzagstrip or ribbon disposed on the outer surface of the cylinder andinsulated therefrom, the center line of the ribbon being parallel to theaXis of the cylinder, successive wrappings of insulating andheat-conducting material wound over the resistance strip, and a closewrapping of band wire surrounding the assembled device and forcing itsparts together to increase the heat-conductivity from the resistanceribbon to the walls of the cylinder.

In testimony whereof, I have hereunto subscribed my name this 21st dayof July, 1908.

WILLIAM S. HADAWAY, JR. Witnesses:

RUSSELL BARBOUR, BIRNEY HINES.

